Such equipment must generally be cooled. A known-art cooling method consists in having deionized, cooled water circulate in the equipment in question. The circulation of the water is ensured using pumps requiring a significant amount of electrical power, on the order of 5-30 kVA.
These pumps are supplied with electrical power by a power supply external to the equipment in question. In order to maintain an appropriate deionization level in the cooling water circuit, the pumps must be supplied during the normal operation of the equipment to be cooled, i.e., whilst the latter is running and had by the power grid, but also when the equipment is stopped and not powered up. In fact, it is generally not permitted to run electrical power through the equipment unless the deionization level of the cooling water is sufficient.